Linear synthesis of the Chol-1 ganglioside core tetrasaccharide and disialyl T antigen glycan using a 5-ureido-sialyl donor.

Herein we describe the linear synthesis of a tetrasaccharyl sialoglycan found in both the Chol-1 ganglioside core and disialyl T antigen. The synthesis featured sialylation with a C5-ureido-modified sialyl donor followed by selective isolation of the desired α-sialoside via 1,5-lactamization. This methodology enables the linear synthesis of sialoglycans and provides practical access to biologically important carbohydrate molecules.

A 5-Ureido-Modified Sialyl Donor: A Tool for the Synthesis of α-Sialosides.

A novel method for the synthesis of α-sialosides using a newly developed 5-ureido-modified sialyl donor is reported. The donor was found to be useful for α-selective sialidation with various glycosyl acceptors, forming α(2,6)Glc, α(2,6)Gal, and α(2,3)Gal linkages in excellent yield and with stereoselectivity. Furthermore, α-sialoside was easily isolated from the reaction mixture by the 1,5-lactamization method under mild conditions.